1. Field of the Invention
This invention relates to a method of manufacturing reinforced optical fiber, and, in particular, to a method for manufacturing optical fiber having a predetermined length thereof covered with a reinforcing coating.
2. Description of Related Art
Optical fibers are very fragile. Use of such fibers in a environment which subjects them to stresses requires some form of reinforcement. Without reinforcement the stresses and environmental forces imposed on the fibers may result in breakage. More significantly, however, is the creation of microcracks and microbends in the optical fiber the quantity and severity of which are directly related to reduced quality of optical signals passing through the fiber.
The need for reinforced optical fibers is particularly significant where the fibers are subjected to substantial "G" loads, such as when they are used in or for communication with missiles or artillery projectiles. Applicant's copending application, Ser. No. 032,448, filed Mar. 31, 1987, now U.S. Pat. No. 4,770,370 discloses a particular use of optical fibers for communication with a tube launched projectile where the fibers are subjected to substantial stress during launch. After the projectile is launched, the fiber which streams from the projectile during its flight is not subjected to the same stresses. Accordingly, in such a use, only a predetermined length of the optical fiber needs to be reinforced. After the launch stress, regular optical fiber can be used. Because the optical fiber is preferrably continuous, a method for reinforcing a predetermined length of a continuous fiber is required. Additionally, it is necessary to have a gradual transition between the reinforced fiber and the regular fiber to preclude a step in the fiber thickness. Such a step not only would provide a surface on which the fiber could snag, but also would constitute a fulcrum about which the fiber could bend thereby concentrating flexing stresses at one point.
The subject invention provides a method of manufacturing a optical fiber having a strong but moderately flexible reinforcing coating which will protect the fiber from a hostile environment and from stress imposed on it and from wear and abrasion. The method of the invention also produces optical fiber which may be reinforced for a predetermined length after which the reinforcing coating is gradually reduced to nothing.
Other objects nd advantages will be set forth in part in the description which follows, and in part will be apparent from the description, or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.